Sailboat system for controlled gibing

ABSTRACT

A system for controlling the jibe movements of a sailboat boom (4), which boom has an outer free end (5) connected to the boat (4) via a sheeting arrangement (6), and an inner end (7) fixed to the mast (3) via a pivot joint (8). A hydraulic actuator (13) is connected with the inner boom end (7) at the pivot joint (8) via a vertically extending axle (9). The actuator can be controlled to swing the boom over the centerline of the boat during a jibing maneuver, as well as can be adjusted to perform a momentum acting against the swinging of the boom eliminating violent, uncontrolled jibing maneuvers.

FIELD OF THE INVENTION

The present invention concerns a system for controlling the jibemovements of a sailboat boom , which boom has an outer free endconnected to the boat via a sheeting arrangement, and an inner end fixedto the mast via a pivot joint.

CLOSET PRIOR ART

The crossover of the boom is traditionally initiated by a ruddercontrolled change in the sailing direction of the boat, and by haulingand subsequent releasing of the sheeting arrangement to force the boomover the centerline of the boat. When the jibing manoeuvre is carriedout with a larger sailboat, the crossover of the boom is normally verysudden and violent, especially because the high and dangerous boomvelocities is reached at angular boom move-ments around the centerline.When the manoeuvre is carried out in strong winds and rough seaconditions, it may be intentional or unintentional, the result can bedisastrous, both for the rigmaterial as well as for a person, who is hitby the boom, sheet or other moving parts.

A system that avoids a violent action of the boom at an unintentionalgibing manoeuvre, is the well known preventer system comprising a fixedline arrangement attached to the boom, and which runs forward to a safeattachment point on the boat, so that the boom is kept fixed at thatperpendicular position in question. At an unintentional jibe this systemleaves one with a backwinded sail and an uncontrolled vessel, which canonly be brought under control by releasing the arrangement whereafterthe boom is totally uncontrolled. Further uncontrollable situationsarises if the outer boom end and the sail is dipped into the watercaused by rolling movements of the boat.

Other known systems acts as springs by urging the boom into asubstantially perpendicular position. These systems does not either giveany control of the boom movements, mainly because they are out offunction when the boom is approaching the centerline of the boat. Thepassover of the boom will therefore still be violent and uncontrolledwith this system.

U.S. Pat. No. 5,333,567 describes yet another system comprising apassive reacting pneumatic cylinder, the one end of which is connectedto the boom and the other end of which is connected to a fixed point onthe boat in distance behind the mast. The distance between theconnection point on the boom and the fixed point on the deck of the boatwill therefore change when the boom is pivoted and the piston of thecylinder will have to move so that a pressure is build up in thecylinder by the instant closure of a throttle opening and the cylinderactuates a passive force during further swinging of the boom. Thissystem is unable to control the boom movement when the boom isapproaching the centerline. When the boom has reached the centerline itis totally out of control. Remembering that the high unwanted boomvelocities initiated around the centerline position, the system is oflimited use.

OBJECT

To put forward a simple and reliable system for controlling the jibemovement of a boom.

THE NOVELTY OF THE INVENTION

The novel system is characterized in that a hydraulic actuator isconnected with the inner boom end at the pivot joint, which hydraulicactuator is transferring a passive momentum to the inner boom end actingagainst boom movements.

Advantages.

Hereby is obtained an unforeseen simple system, which controls the jibemovements of a sailboat boom in a reliable manner, without any risk ofdamaging the rigging or enduring any persons. The system gives the totalcontrol of the angular motion of the boom within every angular sectionof the 180 degrees travel of the boom from the one side perpendicularposition, passing the centerline position and to the other sideperpendicular position.

Mode of Operation.

The hydraulic actuator transfers a pivoting momentum to the boomdirectly in the pivot joint at every angular motion of the boom. Whenthe boom is swung from a perpendicular position at the one side of theboat and to a perpendicular position at the other side passing thecenterline position, the boom movement will have to act against thepassive momentum whereby the angular velocity of the boom will bereduced to a safe limit under all wind conditions. Should the boom startup an unintentional jibing manoeuvre by swinging of its own motion, theactuator will still act with a momentum against the pivoting of the boomslowing down the violent swinging in a controlled manner as well.

Advantageous Embodiments.

Expedient embodiments according to the invention is put forward in thesubclaims.

It should further be mentioned that when the system comprises ahydraulic valve function limiting the flow of the pressure media in theactuator, the angular velocity of the boom is reduced to predeterminedsafe level.

When the system comprises a safety valve limiting the availablehydraulic pressure in the actuator, an upper limit is set for the activemomentum, which can be trans-ferred to the pivot joint end of the boom,whereby damage of the boom and the system is avoided should the boom beobstructed in its angular movement.

When the system comprises a control valve shutting off the flow of thepressure media except to the safety valve, the angular boom movement canbe stopped and subsequently up-started at any desirable angular positionin an expedient manner, which for example is convenient when trimmingthe backstays of the boats rigging during the gibe.

When the actuator comprises a working machine for trans-ferring anactive momentum to the pivot joint end of the boom, an activelycontrolled boom movement is possible.

The working machine can in a very expedient embodiment be carried out asa cylinder.

DESCRIPTION OF THE DRAWING

The invention will be explained more fully below with reference to thedrawing, in which

FIG. 1 is a schematic side view of a sailboat equipped with the deviceaccording to the invention,

FIG. 2 shows the same, seen from above during an articulatedjibemanoeuvre,

FIG. 3 is a schematic side view of part of the device, comprising avertically extending axle connected to the boom at the pivot joint onthe mast,

FIG. 4 shows another part of the device comprising an actuator, seenfrom above, and

FIG. 5 shows another embodiment of the actuator.

DETAILED DESCRIPTION OF ADVANTAGEOUS EMBODIMENTS

The sailboat 1 shown in FIG. 1 comprises a mainsail 2, which is hoistedon a mast 3 and is fixed to a boom 4. The boom 4 has an outer free end 5connected to the boat 1 via a sheeting arrangement 6, and an inner end 7fixed to the mast 3 via a pivot joint 8. By this traditional arrangementthe boom is allowed to approach an angle of up until approximately 90degrees to the centerline of the boat, when the boat is running beforethe wind W, as shown in FIG. 2. The approach angle of the boom 4 isadjusted by hauling or releasing the sheeting arrangement 6. Duringjibing manoeuvres the boom must be swung from its essentiallyperpendicular position at the one side of the boat, and over thecenterline to a perpendicular position at the other side of the boat.

The crossover of the boom is traditionally initiated by a ruddercontrolled change in the sailing direction of the boat, and by haulingand subsequent releasing of the sheeting arrangement to force the boomover the centerline of the boat. When the jibing manoeuvre is carriedout with a larger sailboat, the cross over of the boom is normally verysudden and violent. When the manoeuvre is carried out in strong windsand rough sea conditions, it may be intentional or unintentional, theresult can be disastrous, both for the rigmaterial as well as for aperson, who is hit by the boom, sheet or another moving part.

Preferred embodiments of the system according to the invention shall befurther explained, and comprises an actuator which is connected to theinner boom end at the pivot joint 8. The connection comprises avertically extending axle 9, the upper end 10 of which is rigidlyconnected to the inner boom end 7 at the pivot joint 8. The angularmotion of the boom 4 will hereby follow the same angular motion as theaxle 9 does. The axle 9 is fixed to the mast 3 by way of fittings 11, 12comprising bushings for support of the axle. The lower end 11 of theaxle 9 is connected to the actuator, as shown in FIGS. 4 and 5.

According to the one preferred embodiment shown in FIG. 4, the actuatorcan be in the form of hydraulic cylinders 13 incorporated in a hydraulicsystem 14, which is installed under the deck of the boat. The pistonrods 15 of the hydraulic cylinders 13 are extended by toothed racks 16,which is in engagement with a common gearwheel 17 fixedly mounted to thelower end 11 of the axle 9.

The hydraulic system comprises conventional control means in the form ofa safety/overload valve 18, an adjustable throttle valve 19, a controlvalve 20, as well as a pump 21 and a tank 22 for the hydraulic pressuremedia all connected together via conduits 23.

The control valve 20 is advantageously installed so that it can beactivated directly from the cockpit of the sail-boat 1.

In the most simple form of the system, it advantageously comprises athrottle valve 19, whereby the oil will be throttled when a maximum oilflow is reached in the cylinders 13. The hydraulic cylinders can herebyact as passive resistance means for transferring a passive momentumagainst the boom movement, so that the angular velocity of the boomalways is slowed down to a predetermined safe level under all gibingmanoeuvres. This is especially expedient in the case of an uncontrolledjibe, as the boom movement is slowed down to a safe level.

By guiding oil pressure to the appropriate sides of the pistons of thehydraulic cylinders 13, an active control of the boom movement can alsobe performed. Thereby the toothed racks 16 can be brought to travelforth and back so that the gearwheel 17 is rotated and active momentumis brought to the axle 9. The active control of the boom is limited inspeed and momentum by the valves 18 and 19.

A jibing manoeuvre can hereby be carried out in an actively controlledmanner by one person who activates the control valve 20, advantageouslyby turning a knob to the right when the boom should be turned over froma position at the left side of the boat to the right side or visa versa.Hereby is obtained a system for carrying out fully controllable jibingmanoeuvres without the risk of damaging any material or persons. Ifturning of the control valve 20 is halted during any jibe the boom willsimply stop in that corresponding angular position so that backstays ofthe rig can be trimmed before the boom is allowed to fulfil the angularmotion.

Another advantageously embodiment is shown in FIG. 5, where the axle 9is guided directly into the housing 26 of a hydraulic working machine24. The axle is equipped with a flap 25, which is under influence of oilpressure. The remaining parts of the hydraulic control system can belaid out as it is shown in FIG. 4. In the passive control mode, the flapacts against the oil pressure as in the case of the cylinders. In theactive control mode the flap is driven by active oil pressure to the oneor the other side in the housing with a rotation of the axle 9 as aresult, whereby the boom is forced to conduct an angular motion.

It should be mentioned that a great bending momentum is transferred inthe fixed connection between the upper end 10 of the boom 4 and theinner end 7 of the boom 4, so that a very strong connection isnecessary. Such a connection could comprise the traditional vang orkickingstrap means as well as other stiffening means.

Careful testing have been carried out with a system for a sloopriggedsailboat with an overall length of 75 feet. The length of the boom is 8m and the sailarea of the mainsail is 100 m2. At a windstrength ofBeaufort 6 the windspeed is approximately 11 m/s, which gives acalculated sailpressure of 100 N/m2. The calculated momentum of the axle9 is at this pressure approximately 27000 N/m. The momentum to betransferred to and from the hydraulic actuator can hereby be calculatedas a simple matter of routine, as well as the necessary strength of theaxle 9 can be calculated within safe margins.

It should be mentioned that other expedient embodiments can be carriedout within the scope of the invention comprising other actuator meanssuch as a conventional motor connected to the pivot joint via a gearbox.

I claim:
 1. A system for controlling the jibe movements of a sailboatboom, which boom has an outer free end connected to the boat via asheeting arrangement, and an inner end fixed to the mast via a pivotjoint, comprising a hydraulic actuator connected with the inner boom endat the pivot joint, said hydraulic actuator transferring a passivemomentum (M) to the inner boom end acting against boom movements.
 2. Asystem according to claim 1, further comprising an axle connecting theinner boom end and the actuator which is substantially parallel with themast.
 3. A system according to claim 2 wherein the axle has an upper endwhich is fixed to the inner boom end at the pivot joint so that the axlefollows the same angular motion as the boom, and the lower end of theaxle is connected to the actuator.
 4. A system according to claim 1,wherein the axle has an upper end which is fixed to the inner boom endat the pivot joint so that the axle follows the same angular motion asthe boom, and the lower end of the axle is connected to the actuator. 5.A system according to claim 1, wherein the connection between the innerboom end and the actuator comprises engaging, toothed segments.
 6. Asystem according to claim 5, wherein the toothed segments comprise atleast one pair of an engaging gearwheel and rack wherein the gearwheelis in connected with one of the inner end of the boom and the actuator,and the rack is connected to other of the boom and the actuator.
 7. Asystem according to claim 1 further comprising a hydraulic valvelimiting the flow of the pressure media in the actuator, to control theangular velocity of the boom.
 8. A system according to claim 1 furthercomprising a safety valve for limiting the available hydraulic pressurein the actuator to set an upper limit for the active momentum, which canbe transferred to the pivot joint end of the boom.
 9. A system accordingto claim 1 further comprising a control valve for shutting off the flowof the pressure media except to the safety valve to stop and start theangular boom movement at any desirable angular position.
 10. A systemaccording to claim 1 wherein the actuator comprises a working machinefor transferring an active momentum (M) to the pivot joint end of theboom to produce an actively controlled boom movement.
 11. A systemaccording to claim 10 wherein the working machine comprises a hydrauliccylinder.